A closed circuit is formed by connecting both ends of two different metal conducting wires to one another and a temperature difference is applied to both ends, thereby generating a potential difference between two contact points. A phenomenon described above is designated as a thermoelectric phenomenon. The potential difference generated herein is designated as a thermoelectric force.
Thermoelectric devices use the thermoelectric phenomenon described above. Thermoelectric devices show Seebeck effect and Peltier effect. Both ends of two kinds of metals or semiconductors join one another and a temperature difference is applied to both ends, thereby generating an electromotive force in a circuit. This is designated as Seebeck effect. Two kinds of metals or semiconductors join one another and a current is applied, thereby absorbing or generating heat at a join. This is designated as Peltier effect.
When a single thermocouple is used to measure properties of a thermoelectric device, although using any one of a direct current and an alternating current, it is difficult to heat a contact point of the thermocouple using Peltier effect simultaneously with measuring a temperature of the contact point of the thermocouple using Seebeck effect.